[(7 1-70) 2 +(72-70) 2 +(69-70) 2 +(68-70) 2 +(70-70) 2 ]=2

The standard deviation s is

The range is 4.

(2) Mathematical standard score of a = (71-70).

=

English standard score =(88-85)÷6=

∵

>

So A's math score is better.